1. Field of the Invention
The invention relates in general to a wireless communication system, and more particularly to a wireless communication receiver and an auto gain control (AGC) method thereof.
2. Description of the Related Art
FIG. 1 shows a schematic diagram of a conventional wireless communication receiver. Referring to FIG. 1, a conventional wireless communication receiver 1 includes an antenna 11, a low noise amplifier (LNA) 121, a down-converting circuit 123, a filter 124, a variable gain amplifier (VGA) 125, an analog-to-digital converter (ADC) 13, a processing circuit 14, and a received signal strength indicator (RSSI) circuit 15. The processing circuit 14 includes an auto gain control (AGC) circuit 142, which includes a storage unit 1421 for storing an RSSI mapping table.
The ADC 13 and the processing circuit 14 are configured to process an amplitude range of an input signal. When the amplitude of the input signal is not appropriately controlled (adjusted), the amplitude range processed by the ADC 13 may not be effectively utilized if the signal strength received is too weak. In contrast, a signal will be clipped by the ADC 13 if the signal strength received is too strong such that the conversion of the ADC 13 and demodulation of the processing circuit 14 have undesirable effect.
Therefore, amplitude of a wireless signal is appropriately amplified or reduced through the AGC circuit 142 to satisfy processing amplitude range of the ADC 13 and the processing unit 14. In a conventional solution, the amplitude of the wireless signal is adjusted in coordination with the RSSI circuit 15 and the RSSI mapping table, inferring that design costs of the chip are increased due to the storage unit 1421 for storing the RSSI mapping table and the RSSI circuit 15.